Re: [PATCH 19/19] perf: Garbage-collect event_init checks

Hi Robin,

kernel test robot noticed the following build warnings:

[auto build test WARNING on linus/master]
[also build test WARNING on v6.17-rc1 next-20250814]
[cannot apply to perf-tools-next/perf-tools-next tip/perf/core perf-tools/perf-tools acme/perf/core]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Robin-Murphy/perf-arm-cmn-Fix-event-validation/20250814-010626
base:   linus/master
patch link:    https://lore.kernel.org/r/ace3532a8a438a96338bf349a27636d8294c7111.1755096883.git.robin.murphy%40arm.com
patch subject: [PATCH 19/19] perf: Garbage-collect event_init checks
config: i386-randconfig-003-20250814 (https://download.01.org/0day-ci/archive/20250814/202508141524.QVgoOKMD-lkp-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org/config)
compiler: clang version 20.1.8 (https://github.com/llvm/llvm-project 87f0227cb60147a26a1eeb4fb06e3b505e9c7261)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250814/202508141524.QVgoOKMD-lkp-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <[email protected]>
| Closes: https://lore.kernel.org/oe-kbuild-all/202508141524.QVgoOKMD-lkp-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org/

All warnings (new ones prefixed by >>):

>> arch/x86/events/intel/uncore_snb.c:905:24: warning: unused variable 'hwc' [-Wunused-variable]
     905 |         struct hw_perf_event *hwc = &event->hw;
         |                               ^~~
   1 warning generated.


vim +/hwc +905 arch/x86/events/intel/uncore_snb.c

92807ffdf32c38 arch/x86/kernel/cpu/perf_event_intel_uncore_snb.c Yan, Zheng              2014-07-30  896  
92807ffdf32c38 arch/x86/kernel/cpu/perf_event_intel_uncore_snb.c Yan, Zheng              2014-07-30  897  /*
9aae1780e7e81e arch/x86/events/intel/uncore_snb.c                Kan Liang               2018-05-03  898   * Keep the custom event_init() function compatible with old event
9aae1780e7e81e arch/x86/events/intel/uncore_snb.c                Kan Liang               2018-05-03  899   * encoding for free running counters.
92807ffdf32c38 arch/x86/kernel/cpu/perf_event_intel_uncore_snb.c Yan, Zheng              2014-07-30  900   */
92807ffdf32c38 arch/x86/kernel/cpu/perf_event_intel_uncore_snb.c Yan, Zheng              2014-07-30  901  static int snb_uncore_imc_event_init(struct perf_event *event)
92807ffdf32c38 arch/x86/kernel/cpu/perf_event_intel_uncore_snb.c Yan, Zheng              2014-07-30  902  {
92807ffdf32c38 arch/x86/kernel/cpu/perf_event_intel_uncore_snb.c Yan, Zheng              2014-07-30  903  	struct intel_uncore_pmu *pmu;
92807ffdf32c38 arch/x86/kernel/cpu/perf_event_intel_uncore_snb.c Yan, Zheng              2014-07-30  904  	struct intel_uncore_box *box;
92807ffdf32c38 arch/x86/kernel/cpu/perf_event_intel_uncore_snb.c Yan, Zheng              2014-07-30 @905  	struct hw_perf_event *hwc = &event->hw;
92807ffdf32c38 arch/x86/kernel/cpu/perf_event_intel_uncore_snb.c Yan, Zheng              2014-07-30  906  	u64 cfg = event->attr.config & SNB_UNCORE_PCI_IMC_EVENT_MASK;
92807ffdf32c38 arch/x86/kernel/cpu/perf_event_intel_uncore_snb.c Yan, Zheng              2014-07-30  907  	int idx, base;
92807ffdf32c38 arch/x86/kernel/cpu/perf_event_intel_uncore_snb.c Yan, Zheng              2014-07-30  908  
92807ffdf32c38 arch/x86/kernel/cpu/perf_event_intel_uncore_snb.c Yan, Zheng              2014-07-30  909  	pmu = uncore_event_to_pmu(event);
92807ffdf32c38 arch/x86/kernel/cpu/perf_event_intel_uncore_snb.c Yan, Zheng              2014-07-30  910  	/* no device found for this pmu */
3f710be02ea648 arch/x86/events/intel/uncore_snb.c                Kan Liang               2025-01-08  911  	if (!pmu->registered)
92807ffdf32c38 arch/x86/kernel/cpu/perf_event_intel_uncore_snb.c Yan, Zheng              2014-07-30  912  		return -ENOENT;
92807ffdf32c38 arch/x86/kernel/cpu/perf_event_intel_uncore_snb.c Yan, Zheng              2014-07-30  913  
92807ffdf32c38 arch/x86/kernel/cpu/perf_event_intel_uncore_snb.c Yan, Zheng              2014-07-30  914  	/* check only supported bits are set */
92807ffdf32c38 arch/x86/kernel/cpu/perf_event_intel_uncore_snb.c Yan, Zheng              2014-07-30  915  	if (event->attr.config & ~SNB_UNCORE_PCI_IMC_EVENT_MASK)
92807ffdf32c38 arch/x86/kernel/cpu/perf_event_intel_uncore_snb.c Yan, Zheng              2014-07-30  916  		return -EINVAL;
92807ffdf32c38 arch/x86/kernel/cpu/perf_event_intel_uncore_snb.c Yan, Zheng              2014-07-30  917  
92807ffdf32c38 arch/x86/kernel/cpu/perf_event_intel_uncore_snb.c Yan, Zheng              2014-07-30  918  	box = uncore_pmu_to_box(pmu, event->cpu);
92807ffdf32c38 arch/x86/kernel/cpu/perf_event_intel_uncore_snb.c Yan, Zheng              2014-07-30  919  	if (!box || box->cpu < 0)
92807ffdf32c38 arch/x86/kernel/cpu/perf_event_intel_uncore_snb.c Yan, Zheng              2014-07-30  920  		return -EINVAL;
92807ffdf32c38 arch/x86/kernel/cpu/perf_event_intel_uncore_snb.c Yan, Zheng              2014-07-30  921  
92807ffdf32c38 arch/x86/kernel/cpu/perf_event_intel_uncore_snb.c Yan, Zheng              2014-07-30  922  	event->cpu = box->cpu;
1f2569fac6c6dd arch/x86/events/intel/uncore_snb.c                Thomas Gleixner         2016-02-22  923  	event->pmu_private = box;
92807ffdf32c38 arch/x86/kernel/cpu/perf_event_intel_uncore_snb.c Yan, Zheng              2014-07-30  924  
e64cd6f73ff5a7 arch/x86/events/intel/uncore_snb.c                David Carrillo-Cisneros 2016-08-17  925  	event->event_caps |= PERF_EV_CAP_READ_ACTIVE_PKG;
e64cd6f73ff5a7 arch/x86/events/intel/uncore_snb.c                David Carrillo-Cisneros 2016-08-17  926  
92807ffdf32c38 arch/x86/kernel/cpu/perf_event_intel_uncore_snb.c Yan, Zheng              2014-07-30  927  	event->hw.idx = -1;
92807ffdf32c38 arch/x86/kernel/cpu/perf_event_intel_uncore_snb.c Yan, Zheng              2014-07-30  928  	event->hw.last_tag = ~0ULL;
92807ffdf32c38 arch/x86/kernel/cpu/perf_event_intel_uncore_snb.c Yan, Zheng              2014-07-30  929  	event->hw.extra_reg.idx = EXTRA_REG_NONE;
92807ffdf32c38 arch/x86/kernel/cpu/perf_event_intel_uncore_snb.c Yan, Zheng              2014-07-30  930  	event->hw.branch_reg.idx = EXTRA_REG_NONE;
92807ffdf32c38 arch/x86/kernel/cpu/perf_event_intel_uncore_snb.c Yan, Zheng              2014-07-30  931  	/*
92807ffdf32c38 arch/x86/kernel/cpu/perf_event_intel_uncore_snb.c Yan, Zheng              2014-07-30  932  	 * check event is known (whitelist, determines counter)
92807ffdf32c38 arch/x86/kernel/cpu/perf_event_intel_uncore_snb.c Yan, Zheng              2014-07-30  933  	 */
92807ffdf32c38 arch/x86/kernel/cpu/perf_event_intel_uncore_snb.c Yan, Zheng              2014-07-30  934  	switch (cfg) {
92807ffdf32c38 arch/x86/kernel/cpu/perf_event_intel_uncore_snb.c Yan, Zheng              2014-07-30  935  	case SNB_UNCORE_PCI_IMC_DATA_READS:
92807ffdf32c38 arch/x86/kernel/cpu/perf_event_intel_uncore_snb.c Yan, Zheng              2014-07-30  936  		base = SNB_UNCORE_PCI_IMC_DATA_READS_BASE;
9aae1780e7e81e arch/x86/events/intel/uncore_snb.c                Kan Liang               2018-05-03  937  		idx = UNCORE_PMC_IDX_FREERUNNING;
92807ffdf32c38 arch/x86/kernel/cpu/perf_event_intel_uncore_snb.c Yan, Zheng              2014-07-30  938  		break;
92807ffdf32c38 arch/x86/kernel/cpu/perf_event_intel_uncore_snb.c Yan, Zheng              2014-07-30  939  	case SNB_UNCORE_PCI_IMC_DATA_WRITES:
92807ffdf32c38 arch/x86/kernel/cpu/perf_event_intel_uncore_snb.c Yan, Zheng              2014-07-30  940  		base = SNB_UNCORE_PCI_IMC_DATA_WRITES_BASE;
9aae1780e7e81e arch/x86/events/intel/uncore_snb.c                Kan Liang               2018-05-03  941  		idx = UNCORE_PMC_IDX_FREERUNNING;
92807ffdf32c38 arch/x86/kernel/cpu/perf_event_intel_uncore_snb.c Yan, Zheng              2014-07-30  942  		break;
24633d901ea44f arch/x86/events/intel/uncore_snb.c                Vaibhav Shankar         2020-08-13  943  	case SNB_UNCORE_PCI_IMC_GT_REQUESTS:
24633d901ea44f arch/x86/events/intel/uncore_snb.c                Vaibhav Shankar         2020-08-13  944  		base = SNB_UNCORE_PCI_IMC_GT_REQUESTS_BASE;
24633d901ea44f arch/x86/events/intel/uncore_snb.c                Vaibhav Shankar         2020-08-13  945  		idx = UNCORE_PMC_IDX_FREERUNNING;
24633d901ea44f arch/x86/events/intel/uncore_snb.c                Vaibhav Shankar         2020-08-13  946  		break;
24633d901ea44f arch/x86/events/intel/uncore_snb.c                Vaibhav Shankar         2020-08-13  947  	case SNB_UNCORE_PCI_IMC_IA_REQUESTS:
24633d901ea44f arch/x86/events/intel/uncore_snb.c                Vaibhav Shankar         2020-08-13  948  		base = SNB_UNCORE_PCI_IMC_IA_REQUESTS_BASE;
24633d901ea44f arch/x86/events/intel/uncore_snb.c                Vaibhav Shankar         2020-08-13  949  		idx = UNCORE_PMC_IDX_FREERUNNING;
24633d901ea44f arch/x86/events/intel/uncore_snb.c                Vaibhav Shankar         2020-08-13  950  		break;
24633d901ea44f arch/x86/events/intel/uncore_snb.c                Vaibhav Shankar         2020-08-13  951  	case SNB_UNCORE_PCI_IMC_IO_REQUESTS:
24633d901ea44f arch/x86/events/intel/uncore_snb.c                Vaibhav Shankar         2020-08-13  952  		base = SNB_UNCORE_PCI_IMC_IO_REQUESTS_BASE;
24633d901ea44f arch/x86/events/intel/uncore_snb.c                Vaibhav Shankar         2020-08-13  953  		idx = UNCORE_PMC_IDX_FREERUNNING;
24633d901ea44f arch/x86/events/intel/uncore_snb.c                Vaibhav Shankar         2020-08-13  954  		break;
92807ffdf32c38 arch/x86/kernel/cpu/perf_event_intel_uncore_snb.c Yan, Zheng              2014-07-30  955  	default:
92807ffdf32c38 arch/x86/kernel/cpu/perf_event_intel_uncore_snb.c Yan, Zheng              2014-07-30  956  		return -EINVAL;
92807ffdf32c38 arch/x86/kernel/cpu/perf_event_intel_uncore_snb.c Yan, Zheng              2014-07-30  957  	}
92807ffdf32c38 arch/x86/kernel/cpu/perf_event_intel_uncore_snb.c Yan, Zheng              2014-07-30  958  
92807ffdf32c38 arch/x86/kernel/cpu/perf_event_intel_uncore_snb.c Yan, Zheng              2014-07-30  959  	/* must be done before validate_group */
92807ffdf32c38 arch/x86/kernel/cpu/perf_event_intel_uncore_snb.c Yan, Zheng              2014-07-30  960  	event->hw.event_base = base;
92807ffdf32c38 arch/x86/kernel/cpu/perf_event_intel_uncore_snb.c Yan, Zheng              2014-07-30  961  	event->hw.idx = idx;
92807ffdf32c38 arch/x86/kernel/cpu/perf_event_intel_uncore_snb.c Yan, Zheng              2014-07-30  962  
8041ffd36f42d8 arch/x86/events/intel/uncore_snb.c                Kan Liang               2019-02-27  963  	/* Convert to standard encoding format for freerunning counters */
8041ffd36f42d8 arch/x86/events/intel/uncore_snb.c                Kan Liang               2019-02-27  964  	event->hw.config = ((cfg - 1) << 8) | 0x10ff;
8041ffd36f42d8 arch/x86/events/intel/uncore_snb.c                Kan Liang               2019-02-27  965  
92807ffdf32c38 arch/x86/kernel/cpu/perf_event_intel_uncore_snb.c Yan, Zheng              2014-07-30  966  	/* no group validation needed, we have free running counters */
92807ffdf32c38 arch/x86/kernel/cpu/perf_event_intel_uncore_snb.c Yan, Zheng              2014-07-30  967  
92807ffdf32c38 arch/x86/kernel/cpu/perf_event_intel_uncore_snb.c Yan, Zheng              2014-07-30  968  	return 0;
92807ffdf32c38 arch/x86/kernel/cpu/perf_event_intel_uncore_snb.c Yan, Zheng              2014-07-30  969  }
92807ffdf32c38 arch/x86/kernel/cpu/perf_event_intel_uncore_snb.c Yan, Zheng              2014-07-30  970  

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